I had my dry cleaner steam my extra length cathedral veil. Note too that you can steam the gathering if it’s too poofy. After it was steamed, I used a bobby pin to hook the comb onto a wire hanger (no wire hangers!), put that on the closet frame in a spare room and spread it out. I had also for a time had it on the headboard spread over the bed in the spare room (but people needed to use it when we got closer to the wedding).

I used a home steamer, and it worked out OK. It does have a "deflating" effect on the thing, though. It was significantly less stiff and poufy, but I actually was happy about that. (The stiffness did return after a couple days, so it’s not like it stayed limp or anything like that, in case you’re worried about having a wilted veil.)

I was told by my seamstress to simply hang the veil in the bathroom while taking a shower. I hung my incredibly wrinkled veil in the hotel bathroom 2 nights before the wedding and it went through multiple steam baths due to BM’s showers, and the veil was perfect by wedding morning. 🙂